The invention relates to cooking or heating apparatus, and, more particularly, to an improved tunnel oven or broiler for heating food or other products while they are being conveyed through a tunnel within a preselected time.
It has come to be expected in restaurant, industrial, and institutional cooking that greasy foods such as hamburgers, steaks, chops, etc. will tend to flare up and char as grease rendered by the food catches on fire, as will occur when exposed to temperature sufficient for broiling, for example. This is particularly so for beef, pork, and lamb but also occurs with fowl, including chicken, turkey, and duck.
Avoiding such flaming or flaring up of greasy foods is rendered extremely difficult since meat grease, for example, may begin vaporizing at only about 150.degree. F. Therefore, the exposure of grease vapors to even the modest temperature present in ovens and broilers is likely to produce combustion.
One unfortunate aspect of such flaring or flaming of meat and grease in an oven is difficulty, if not impossibility, of accurately maintaining temperature control. This is because the flames and flaring up cause improper response by temperature sensing elements not indicative of the true temperature in the oven.
Further, there is now research data tending to suggest that exposure of food products to direct flame may cause conversion of their organic constituents, or food additives, or preservatives, to carcinogens. Some researchers have even gone so far as to present evidence that the exposure of meat to a grilling surface in excess of 350.degree. F., as on a grill or griddle, may tend to produce carcinogenic substances. The American Cancer Society has suggested that the impingement of flame on meat promotes carcinogens.
As a consequence of the mounting evidence that direct exposure of meats and other food products to flame may be harmful, it is already forbidden in some countries for restaurants or other commercial establishments to serve food which has been cooked by direct exposure to flame, even though this practice is ubiquitious in the United States of America.
In recent years, tunnel ovens have been developed for use in the fast food and industrial cooking field, such as disclosed in Wells U.S. Pat. No. 4,008,996 and Wells U.S. patent application Ser. No. 956,869 now U.S. Pat. No. 4,245,613. Ovens of this type cook by infrared emission from hearth and roof panels within the tunnel such as disclosed in Wells U.S. Pat. No. 3,809,859, for example.
These tunnel ovens have provided a revolutionary new way of cooking which preserves the taste, succulence and moisture of food products. They do not utilize heated air for cooking which tends to dry out food.
An infrared tunnel oven of this type can be used for cooking of steaks, chops, etc. by conveying them through the oven in a pan. This avoids dropping of the grease and cooking of such meats in this way provides an excellent result from the standpoint of preservation and taste of the food product. But, like microwave cooking, the appearance of the cooked product is not fully acceptable in some usages, since it lacks the browned appearance which some customers have grown to accept. Further, the use of pans for conveying the food product through the tunnel oven means that there are pans to be handled and cleaned.
It is desired to provide infrared cooking of various foods, but particularly greasy foods such as steaks, chops, etc., by directly conveying them through a tunnel for exposure to infrared heating, but at temperatures which are sufficiently high that the food will undergo heating of a nature that it undergoes conversion to a most appetizing appearance. Steaks, for example, will take on a degree of rich, taste-tantalizing coloration or browning which is not only acceptable but very appealing to customers.
It has now been discovered by the present inventor that meats, chops, and other greasy food products can now be cooked by infrared heating, with all of its many advantages, but in an oxygen-starved atmosphere which substantially precludes the flaming and flaring of grease, or grease vapors, and the resultant exposure of the food products to direct flame. It has also been found that certain other products can be cooked under such conditions in which otherwise would tend to burn, such as diary products.
Quite apart from the matter of exposing food products to flame, one of the more pressing needs in the field of industrial cooking is to provide a cooking apparatus capable of being utilized in food processing operations, and particularly those where the approval of the U.S. Department of Agriculture is required to satisfy concerns for the sanitary character of the cooking apparatus. In this regard, prior art arrangements of tunnel ovens have not been readily conducive to meeting the stringent U.S.D.A. food processing requirements even though meeting exemplary standards for food service usages.
An object of the present invention is the provision of a tunnel oven-broiler, referred to herein as an infrared tunnel oven, of an improved type for infrared heating of food or other products.
It is a further object of the present invention to provide such a tunnel oven which makes possible substantially flameless cooking of food products, and particularly greasy or other food products which tend to burn or flame up during cooking.
A still further object of the present invention is the provision of such a tunnel oven which provides oxygen-starved cooking of food products to prevent flaring, flaming, grease fires, and other deleterious effects of cooking in very oxydizing atmospheres.
Another object of the present invention is the provision of such a tunnel oven which can provide infrared heating of food and other products at temperatures heretofore not utilizable in tunnel ovens, as well as at different upper and lower temperatures within the tunnel oven having a greater possible differential than heretofore achievable.
Another object of the invention is the provision of such a tunnel oven which provides and promotes temperature control and consistency of cooking for more uniform and more reproducible cooking of food products.
Another object of the invention is the provision of such a tunnel oven which is easily cleanable and capable of meeting stringent sanitary requirements, as well as being of a self-cleaning nature.
A further object of the invention is the provision of such a tunnel oven which can provide continuous heating of food or other products, and with such products being continuously fed into and delivered from the oven, yet is extremely energy efficient, as contrasted with prior art ovens.
A further object of the invention is the provision of such a tunnel oven which is of a modular nature, being adapted for convenient, rapid assembly of modules into desired lengths, as well as equally convenient disassembly or separation of the modules for cleaning, alteration of length, or adaption for different purposes.
Among still other objects of the present invention include the provision of such a tunnel oven which can be relatively economically and simply manufactured, which is reliable and of an extremely durable, long-lasting configuration, and which is very well suited for heavy duty, high-volume commercial usage.
Other objects and features of the invention are in part apparent and in part pointed out hereinbelow.